1. Field of the Invention
The present invention relates to a solution treatment system provided with a solution treatment unit which gives a solution treatment to a substrate such as a semiconductor wafer and to a solution treatment method.
2. Description of the Related Art
In recent years, wiring which constitutes a semiconductor device has been made more microscopic owing to the improvement in the degree of integration of the semiconductor device. With this, the forming technique of the microscopic wiring and securing of its reliability have become important objects. As one of means for attaining these objects, an embedded wiring method which forms wiring by embedding a metal in trenches or connection holes formed in a semiconductor wafer (hereinafter, simply referred to as a xe2x80x9cwaferxe2x80x9d) has come to the force.
As a unit which can carry out such an embedded wiring method, a plating unit which embeds a metal by electrolytic plating in trenches or connection holes formed in a wafer is known. In this plating unit, the metal is embedded in the trenches or the connections holes of the wafer by applying a voltage between a pair of electrodes while the wafer is in contact with a plating solution.
In the plating unit as described above, when the metal is embedded in the trenches or the connection holes of the wafer, an additive contained in the plating solution is consumed with the elapse of time to lower an embedding speed. This reduction in the embedding speed causes decrease in throughput. Therefore, the plating solution, after used for a certain period, is replaced by a new plating solution to suppress the decrease in throughput.
There exists, however, such a problem that the plating solution has to be replaced frequently since the embedding speed starts to lower in a short time.
It is an object of the present invention to provide a solution treatment system and a solution treatment method which can decrease the frequency of replacing a treatment solution by suppressing reduction in solution treatment speed.
A solution treatment system of the present invention comprises: a solution treatment unit which includes a treatment solution tank to store a treatment solution and a pair of electrodes and which gives a solution treatment to a substrate; a treatment solution storage tank which stores the treatment solution; a treatment solution supply system which supplies the treatment solution stored in the treatment solution storage tank to the solution treatment unit; and a dissolved oxygen removing unit which is disposed in the middle of the treatment solution supply system and which removes dissolved oxygen from the treatment solution flowing in the treatment solution supply system. Since the solution treatment system of the present invention is provided with the dissolved oxygen removing unit, the reduction in solution treatment speed can be suppressed to decrease the frequency of replacing the treatment solution.
It is preferable that the solution treatment system described above further comprises: a treatment solution stirring system which stirs the treatment solution stored in the treatment solution storage tank; and a dissolved oxygen removing unit which in disposed in the middle of the treatment solution stirring system and which removes the dissolved oxygen from the treatment solution flowing in the treatment solution stirring system. By providing the treatment solution stirring system and the dissolved oxygen removing unit, the reduction in the solution treatment speed can be further suppressed.
Another solution treatment system of the present invention comprises; a solution treatment unit which includes a treatment solution tank to store a treatment solution and a pair of electrodes and which gives a solution treatment to a substrate; a treatment solution storage tank which stores the treatment solution; a treatment solution supply system which supplies the solution treatment unit with the treatment solution stored in the treatment solution storage tank; a treatment solution stirring system which stirs the treatment solution stored in the treatment solution storage tank; and a dissolved oxygen removing unit which is disposed in the middle of the treatment solution stirring unit and which removes dissolved oxygen from the treatment solution flowing in the treatment solution supply system. Since the solution treatment system of the present invention is provided with the dissolved oxygen removing unit, the reduction in the solution treatment speed can be suppressed to decrease the frequency of replacing the treatment solution.
It is preferable that the solution treatment system described above further comprises a housing accommodating the treatment solution storage tank and an inert gas supply system which supplies an inert gas into an inner part of the housing. The inert gas of the present invention means a nonoxide gas. Specifically, for example, a rare gas such as helium, neon, argon, xenon, and krypton or nitrogen can be named. By providing the housing and the inert gas supply system, oxygen is not easily taken into the treatment solution.
It is preferable that the solution treatment system described above further comprises a dissolved oxygen measuring unit which measures the concentration of the dissolved oxygen contained in the treatment solution. By providing the dissolved oxygen measuring unit, the concentration of the dissolved oxygen can be accurately controlled.
It is preferable that the treatment solution used in the above-described solution treatment system contains an additive. As the additive contained in the treatment solution, for example, a sulfur compound can be named. As the sulfur compound, for example, an organic bivalent sulfur compound can be named. By including the additive in the treatment solution, the solution treatment speed can be made higher. Furthermore, even when the additive is contained in the treatment solution, the consumption of the additive can be suppressed.
The treatment solution used in the above-described solution treatment system may be a plating solution. The use of the plating solution as the treatment solution makes it possible to plate the substrate.
A solution treatment method of the present invention comprises: a dissolved oxygen removing step of removing dissolved oxygen from a treatment solution in a treatment solution storage tank; a treatment solution supply step of supplying a treatment solution tank with the treatment solution from which the dissolved oxygen is removed; and a solution treatment step of bringing a substrate into contact with the treatment solution supplied to the treatment solution tank and passing an electric current through the substrate to give a solution treatment to the substrate. Since the solution treatment method of the present invention comprises the dissolved oxygen removing step, the reduction in solution treatment speed can be suppressed to decrease the frequency of replacing the treatment solution.
The dissolved oxygen removing step described above may be carried out when the treatment solution is supplied to the treatment solution tank. Carrying out the dissolved oxygen removing step when the treatment solution is supplied to the treatment solution tank makes it possible to surely suppress the reduction in the solution treatment speed.
The dissolved oxygen removing step described above may be carried out when the treatment solution in the treatment solution storage tank is stirred. Carrying out the dissolved oxygen removing step when the treatment solution in the treatment solution storage tank is stirred makes it possible to further suppress the reduction in the solution treatment speed.
It is preferable that the solution treatment method described above further comprises an inert gas supply step of supplying an inert gas into an inner part of a housing accommodating the treatment solution storage tank. When the inert gas supply step is included, oxygen is not easily taken into the treatment solution.